This invention relates to supercharged and intercooled internal combustion engines which utilize a rotary piston unit for first stage compression and for final stage expansion.
Rolls-Royce Ltd.
A rotary piston unit was combined with a rotary piston engine by Rolls-Royce Ltd. This engine was designed to operate with compression ignition, i.e. a Diesel engine. To enhance the overall compression ratio and resulting air compression temperature rise, the compressed air discharged from the rotary piston unit was received directly into the rotary piston engine during its intake stroke or intake process. The phase relationship of the rotary pistons was selected to enhance the overall compression process. The volume of the interconnecting passage from the discharge port of the rotary piston unit to the intake port of the rotary piston engine was minimized. The goal was to obtain an overall compression ratio and resulting air temperature rise suitable for compression ignition (Diesel) operation. Several compound rotary piston engines of this type were built and tested during the 1960""s by Rolls-Royce Ltd. of Derby, England. U.S. Pat. No. 3,228,183, dated Jan. 11, 1966, was granted to F. Feller concerning this type of compression ignition engine. Since development work was concluded, when government funding was terminated, it is probable that the test results were not encouraging.
Basic Design Differences
The design concepts of the machine disclosed herein are very different from those disclosed in the above patent granted Rolls-Royce Ltd. The invention disclosed herein is directed toward a large magnitude and very efficient overall compression/expansion ratio machine. The machine uses a rotary piston unit for initial compression and final expansion, an intercooler, and a conventional internal combustion engine. The engine may have one or multiple cylinders, may operate as a two stroke cycle or four stroke cycle, use liquid or gaseous fuel and have spark or other methods for ignition. Normally, the machine includes a compressor discharge check valve adjacent the rotary piston unit and an intercooler between the discharge check valve and the internal combustion piston engine. These two additional components essentially decouple the compression process in the rotary piston unit from the compression process in the engine and enhance the efficiency of the overall compression process. In several forms of this invention, the engine exhaust flow process is phased relative to the expansion process of the rotary piston unit to obtain the maximum expansion work available from the expanding products of combustion, thus maximizing the overall expansion efficiency. This ideal overall expansion process was not possible with the concept Rolls-Royce disclosed in their U.S. Pat. No. 3,228,183.
From the above discussion it is clear that the details of the application of the rotary piston charger per this invention are very different from the prior art as patented by Rolls-Royce Ltd. In this disclosure, rotary piston units are shown in combination with various forms of internal combustion piston engines. The rotary piston unit is uniquely suited for supercharging and final expansion of non-turbocharged piston engines. When used as disclosed herein, very low specific fuel consumption machines can be obtained with reasonable size, weight and cost.
An object of this invention is to significantly increase the magnitude and efficiency of the processes of compression/expansion, and thereby increase power output and reduce specific fuel consumption.
A second object of this invention is to increase the duration of positive torque each cycle thus improve the smoothness of operation of the machine.
A third object of this invention is to reduce the size and weight of the supercharged engine by reducing its displacement for a given power output.
A fourth object of this invention is to increase the normal speed of operation of the engine due to its reduction of size/displacement.
A fifth object of this invention is to minimize the loss of available expansion energy normally incurred when high pressure, hot exhaust gases are vented to atmospheric (exhaust) pressure.
A sixth object of this invention is to reduce the noise produced when the exhaust gases are vented to atmosphere.
A seventh object is to reduce the weight of emissions per horsepower output exhausted from the machine.
A eighth object of this invention is to reduce the temperature of the exhaust gases.
A ninth object of this invention is to use positive displacement components for the compression/expansion processes in the machine.
A tenth object of this invention is to utilize the expander of the rotary piston unit for cranking/starting the machine.
Further objects and advantages of this invention will become apparent from a consideration of the drawings and ensuing descriptions.